I spent 3 months touring NZ, admittedly about 10 years ago now...great times. [y] I am so envious as it is a fantastic place...I can get a bit enthusiastic about it so apologies if the below is a bit overwhelming [:I]
Personally, I'd get out of Auckland as soon as possible - nothing against it, it's just...an average town.
Rotorua is indeed a good place to visit - lots of geysers, thermal pools, and funny coloured lakes. If you have been to Yellowstone, then you will know the score, but it is still definitely worth a trip. Rotorua is also a centre of Maori culture so I'd also suggest attending a hangi, if you can - a ceremonial Maori dinner. Okay, it's all put on for the benefit of the tourists and so feels a bit artificial, but if you can get over that and enter into the spirit (and fancy being taught how to do a haka [:D] by a friendly Maori), it'll give you good memories
One word of warning - be ready for the all-pervading smell of rotten eggs in the town, and it will be on you for days when you leave...!
There are three other things I'd strongly recommend, if you can fit them in:
Lake Taupo - near Rotorua - do a tandem skydive over Lake Taupo, which is frankly enormous - NZd's largest lake. Fantastic experience, espcecially if you have never been skydiving before.
http://www.taupotandemskydiving.com/tandem.htmHamilton - near Auckland, on the way to Rotorua - the glow worm caves are fantastic, as long as you are not claustrophobic. Avoid the mainstream tours if you can, where you drift through on a large boat and it's all a bit Disney. Instead, I strongly recommend black water rafting through them, which is simply the most amazing fun you can have underground. You need to be mobile enough to fit into rubber tractor tyres, and manage some moderate exertion, but it is perfectly safe and there was no problem with my 14-stone and bad back.
http://www.waitomo.com/black-water-rafting.aspx Napier - on the east coast. This is an amazing town, which was demolished by an earthquake in the 30s and rebuilt in completely in Art Deco style (even the McDonalds is the world's only Art Deco McDonalds). It is surrounded by vineyards, so definitely take a vineyard tour. Try and find a small independent tour guide: otherwise you get swept up on a big coach that decants you at an endless series of major vineyards for carefully-controlling tasting and buying opportunities. I went with a small independent operator who took a group of us in a minibus round to some off-the-beaten-track vineyards where we were on our own, able to take our time, chat to the owners, and customise the tour to our taste in wine. Highly recommended [:o)]
EDIT: Pretty sure it was Vince's Wine Tours I used -
http://www.tripadvisor.com/ShowTopic-g2 ... sland.html. Glad to see he's still going strong!
Napier is also close(-ish) to the East Cape - NZ's eastern-most point - so if you fancy being one of the first people in the world to see the sun rise it's worth a drive up there. Not much else to do there, though, and I can speak from personal experience when I say they definitely need more petrol stations up there.
EDIT; just remembered - if you are fit and like hiking, then the Tongariro Crossing is one of the world's best (I'm told...not a hiker, me [:#]). It takes a full day and a lot of uphill walking, but if you want to see some amazing mineral pools, geysers and walk around the rim of an active volcano, this is your bunny. It's just south of Rotorua.
http://www.tongarirocrossing.org.nz/Finally, I'd personally stay in B&Bs rather than hotels - New Zealand is so friendly you'd miss out a lot by saying in the more formal atmosphere of a hotel.
I actually stayed in hostels a lot - yes, I know what you are all thinking [:I] - but while I wouldn't have gone near some with a bargepole, especially in the major cities, some were simply out-of-this world. For example this place -
http://www.kenepuruecolodge.co.nz/index.html - is 30 a night for a private double room and absolutely gorgeous, even if only accessible by water taxi / several days walk...shame it's on the South Island.
One word of warning - wherever you book to stay, make sure it's NOT used by the Kiwi Experience tour group....shudder.
Cheers
Drew